The past few years have been the most decisive and divisive ideological period since the early 1980s, perhaps since the late 1960s. Barack Obama has pursued Keynesian economics on a breathtaking scale, racking up three years of deficitsin excess of a trillion dollars and presiding over a national credit downgrade. In a march of partisan votes, he passed a health-reform plan that relies on unprecedented federal powers to reorganize one-sixth of the economy.

The ultimate success or failure of grand executive ambition is measured by its effect on the other ideological side. Opposition to the Reagan revolution culminated in Walter Mondale — earnest and hapless. Resistance to the Great Society suffered a landslide defeat, as did Barry Goldwater.

Obama’s effect on conservatives has been mixed. He united them in the 2010 congressional elections, which put an end to the inventive period of the Obama revolution. But Obama’s ambition has also revealed a tension within the opposition.

On one side there are Rejectionist Conservatives, who come in a variety of forms. There are libertarians who view federal taxation, except to fund a few night-watchman roles, as theft. There are tea party activists who believe that any federal power must be specifically enumerated in the Constitution — and then interpret the Constitution as if it were the Articles of Confederation. And then there is Ron Paul, who seeks to overturn the Lincoln and Hamilton revolutions.

But Obama’s overreach has also produced another conservative reaction — a Reform Conservatism. The key figure here is Paul Ryan, the main author of two House Republican budgets. The movement’s intellectual headquarters is National Affairs, a journal of small but potent distribution. Its brain trust includes thinkers such as Yuval Levin, James Capretta and Peter Wehner.

The reform movement — being prone to long, self-reflective policy articles — is not hard to summarize.

First, it asserts that America’s massive fiscal crisis is a result of public-sector inefficiency. So it looks for ways to achieve the ends of the welfare state both through more private means and more efficient public means.

Second, it asserts that America’s economic challenge is also a function of public-sector inefficiency and seeks above all to encourage growth — by streamlining the tax code, reducing burdens on competitiveness and showing confidence in market mechanisms and consumer pressure.

Third, Reform Conservatism argues that America’s social problem is largely a function of the collapse of social capital among the poor and seeks to transform the safety net — encouraging responsibility and providing training toward integration in the broader stream of American life.

Reform Conservatism is less ideologically ambitious than Rejectionist Conservatism. It would replace Obamacare, for example, rather than simply abolish it. Similarly, it focuses on education reform — school accountability, parental empowerment and teacher quality — rather than on the demolition of the Education Department. Reform Conservatism tends to be politically pragmatic. In exchange for serious Medicare reform, for example, it would certainly accept a higher portion of gross domestic product taken in taxes to ease cuts in discretionary spending — if those taxes are designed in a way that doesn’t undermine economic growth.

In this political season, Rejectionist Conservatism and Reform Conservatism have been at odds and, on occasion, at war. We’ve seen this conflict in tea party primary insurgencies against establishment Republicans. All of the GOP presidential candidates were forced to make rhetorical concessions to the rejectionist wing.

But the conflict, in the end, was not a close one. Speaker John Boehner has adopted Ryan’s reform approach as the de facto ideology of the House Republican majority. Mitt Romney has embraced the outlines of the Ryan budget and Medicare reform with more enthusiasm than I suspected he would. The internal struggle within conservatism has been difficult, but the outcome has been decisive. Reform Conservatism is intellectually and politically ascendant. It would be the governing agenda of the next Republican administration.

This agenda, in Ryan’s expression, has weaknesses — which I will address more fully in a follow-up column. It is best on the fiscal crisis — which threatens all other purposes of government. It is least creative on the social problem — which is prioritized last and suffers from being overwhelmed by the fiscal crisis.

But the debate in American public life has moved on. It is now between Reform Conservatism and Obama’s surprisingly unreconstructed liberalism — the real battle to come.

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